1. Field of the Invention
The present invention relates to a storage medium storing a calculation processing visualization program, a calculation processing visualization apparatus, and a calculation processing visualization method, and particularly relates to a storage medium storing a calculation processing visualization program, a calculation processing visualization apparatus, and a calculation processing visualization method that visualize the execution status of pipeline processing that is executed by a calculation unit.
2. Description of the Related Art
Computers are now required to execute increasingly complicated software and process larger volumes of data. Calculation units incorporated in such computers are required to improve their processing capacity further. To improve the processing capacity, a calculation unit typically employs pipeline processing, which is one technique to speed up calculation processing. The pipeline processing divides processing caused by a single instruction into a plurality of processes (stages) that are executed in parallel.
For example, the processing caused by a single instruction may be divided into four stages: Instruction Fetch (F), Instruction Decode (D), Instruction Execute (X), and Write-back (W). In this case, for example, Instruction Decode (D) of a first instruction may be executed in parallel with Instruction Fetch (F) of a second instruction. This technique substantially enables as many instructions as the number of stages to be executed in parallel, and consequently speeds up calculation processing.
When a calculation unit having a simple pipeline structure is used to process consecutively some instructions dependent on one another, however, a waiting state occurs and processing efficiency lowers. For example, when the second instruction needs the processing result of the first instruction, the second instruction has to wait until the first instruction is completed. Therefore, to develop a calculation unit, a pipeline that would suppress the occurrence of a waiting state should be designed. A complier and programs intended for the calculation unit with pipeline processing also need be developed so as to fit the pipeline structure of the calculation unit.
Developers of calculation units, compliers, and programs simulate pipeline processing as required to analyze the occurrence of a waiting state. For example, a simulator intended for pipeline processing receives the design information and a test program of a target calculation unit, virtually executes the test program, and outputs information indicating the execution status of pipeline processing.
Simulation results obtained in this way are displayed in a visual format easily comprehensible to the developer. One such format known in the art is a waterfall chart showing the stage changes of each pipeline stage in tabular form, in which the vertical axis indicates instructions input into the pipeline and the horizontal axis indicates clock cycles. With one conventional visualization method using such a waterfall chart, a portion where a waiting state occurs is highlighted (refer to Unexamined Japanese Patent Application Publication No. Hei-11-65845, for example).
However, with the technique described in Unexamined Japanese Patent Application Publication No. Hei-11-65845, developers may have difficulties in finding problematic portions that can lower processing efficiency when the developers are required to handle large volumes of simulation-result data. In particular, developers will have more difficulties in finding problematic portions when the test program includes instructions that cause processes forming loops. When the test program includes such instructions, the waterfall chart displays an element indicating an identical process forming each loop the number of times the loop is executed. The execution status of only one or a small number of processes forming the same loop would actually be sufficient for the developers to check problematic portions that can lower processing efficiency. However, the developers may fail to correctly determine each loop simply by comparing in shape elements indicating processes in the waterfall chart.